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Windows 7: Freeview Pixellation on certain channels


18 Apr 2012   #1

Windows 7 Ultimate x64 / x32
 
 
Freeview Pixellation on certain channels

Hi All

I have my mediacenter setup as my main TV with two Compro T100 freeview tuners installed.
When I first installed everything it worked perfectly, all 100 odd channels were crisp and worked perfectly.
Then I had a problem with my antenna and I lost a few channels either saying "No TV Signal for this channel" or the picture is heavily pixellated and the audio stuttering.

I have been troubleshooting it on and off for the last few weeks getting more and more frustrated.
At present certain channels work perfectly, BBC1, BBC2, More4+1, Quest and a few shopping channels and other crap.

But the majority of "common" channels such as ITV, C4, C5, E4 etc are completely unwatchable due to pixelation and broken sound.

I have tested the signal strenth with another standalone freeview box, on which all channels work perfectly and show maximum signal strenth which makes sense considering I'm only about 5 miles from the UK's biggest transmitter.

Googling I found that some people suggested it was a codec or decoder issue, I used MCDU to change that which didn't help.

I suspected that maybe it was a driver issue or something that I had installed so last night I re-installed windows and have not yet installed anythign at all and the exact same problem has occured, BBC1 and 2 work perfectly, most others are useless.
Windows installed the drivers for the tuner cards so I haven't downloaded anything from the Compro website yet. I though I'd see what people on here thought first.

I haven't got the exact specs to hand but...
Xeon CPU
Onboard graphics (G41 Chipset)
Gigabyte motherboard
2x Compro T100 Tuners
4GB RAm
Windows 7 Ultimate 32Bit (previous installation was 64bit)


Anyone have any suggestions?

My System SpecsSystem Spec
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18 Apr 2012   #2

Windows 8.1 Pro RTM x64
 
 

Hi squishio and welcome to Windows 7 Forums

As you are probably aware, digital TV in the UK uses the same channels as the old analog system, i.e. 21-69. With the old system, each broadcast channel (BBC/ITV/C4/C5) was transmitted on a separate channel within the above spectrum (channel spectrum numbers were reused accross the country, but this was arranged so that no interference occurred). With digital, multiple broadcast streams are multiplexed and transmitted on each channel in the above spectrum. Unfortunately, this can lead to cross-contamination and/or breakup of audio/video content. The distance from the transmitter, relative signal strengths of the broadcast streams on the same channel, and atmospheric conditions can all play a part here. Too far from the transmitter, and problems occur due to weak signals and patchy reception of the lesser stations. Conversely, being too close can also cause similar problems due to the strength of some stations being greater than others on the same channel.

You did say that this problem occurred when you had antenna troubles. It might be worth having a look at this, checking the orientation and signal strength. Being so close to the transmitter, you might possibly have signal overload, meaning that the signal is too powerful for the tuners to cope with - the solution being to fit an attenuator to reduce the strength of the signal. Just because another Freeview box gives satisfactory results it doesn't mean to say that others will. It all depends on how well the tuner is able to separate the different streams on each channel.

Have a word with your local aerial installer. It could be that you might need a replacement or some other work carried out such as realignment to the transmitter and the possible fitting of an attenuator.
My System SpecsSystem Spec
18 Apr 2012   #3

Windows 7 Ultimate x64 / x32
 
 

I didn't know that, thanks very much!
So it may have been a foolish mistake thinking my signal was weak and getting a massive ariel...


Seemed like a good idea at the time, though there was always something in the back of my mind telling me I didn't need such a big one due to my location.

I have tested orientation with a signal meter which with its current alignment goes straight to maximum. It is pointing in the same general direction as all the others in the area (towards crystal palace)

So, would getting one of these and having a play be a good idea?

1-20dB variable digital tv aerial signal attenuator | eBay
My System SpecsSystem Spec
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18 Apr 2012   #4

Windows 8.1 Pro RTM x64
 
 

I would seek the advice of a competent aerial installer. They should be able to tell you what sort of aerial is suitable for you, bearing in mind how close you are to the transmitter. They can also supply and fit attenuators, junction boxes, etc., to your particular requirements.
My System SpecsSystem Spec
24 Apr 2012   #5

win 7 ultimate x86
 
 
Check your MCE settings

Just seen your problem and joined so I could answer, I had exactly the same issue and I have the BG HD Freeview dual tuner installed.

After months of playing and changing my ariel I could never figure out why my tele was fine yet my freeview card played up in MCE.

Firstly I went here Freeview on The Wrekin TV transmitter | ukfree.tv - independent free digital TV advice and found out what transmitter I was supposed to be receiving from, as you can see I am using the Wrekin transmitter.

If you scroll down you will see the correct frequency that you need to tune to for specific channels, so for me bbc1 is on 514.0MHz

Now on mediacentre go to settings-tv-guide-edit channels

select a channel (bbc1 in this example), scroll down the options on the left to "Edit Sources". Here you will see all the frequencies MCE pickup during the scan, note there is a record for each frequency for each tuner so in bbc1 I have 18! yes 18 sources which is 9 for each tuner 9 x 2 = 18 obviously.

Simply scroll through the list and enable the options that fit your transmitter (in my case 514.0MHz twice) I also use the arrows on the menu to make them no's 1 & 2 in the list to make sure they are the highest priority.

Unfortunaltly you have to do this for all channels but it is worth the time investment.

From what I could gather MCE will try and select the frequency that has 100% quality but this seems to fail and did for me on the ITV main channels as it trying to tune to a transmitter I was not pointing at.

After setting all my channels (with a quality of 60% showing in MCE) it has been fine with no breakup and after months of digging I found my answer

I hope this helps

Mark
My System SpecsSystem Spec
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 Freeview Pixellation on certain channels




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